Illustrated herein in embodiments are toner processes, and more specifically, emulsion aggregation and coalescence processes. More specifically, disclosed in embodiments are methods for the preparation of toner compositions by a chemical process, such as emulsion aggregation, wherein latex particles, such as latexes containing crystalline or amorphous polymeric particles such as polyester or sulfonated polyester, are aggregated with a wax and a colorant, in the presence of a coagulant such as a polymetal halide or other monovalent or divalent metal coagulants, optionally adding a latex containing further polymeric particles, thereafter stabilizing the aggregates and coalescing or fusing the aggregates such as by heating the mixture above the resin Tg to provide toner size particles, and adding additional coagulant to the surface of the toner particles to establish a desired triboelectric charging characteristic of the toner particles.
A number of advantages are associated with the toner obtained by the processes illustrated herein. For example, the processes provide toner particles having a desired triboelectric charging characteristic, which can range from negative charge, to neutral, to positive charge. These different charging characteristics can be desired depending on the particular image development system being used and thus the required toner charge. For example, negative charged toners are generally used in discharge area development and semi-conductive magnetic brush development systems, while positive charge toners are generally used in charged area development and tri-level development systems.
In order to provide desired toner charge, conventional practice has been to either alter the polymeric resin being used, or apply different post treatments to formed toner particles. However, these alternatives require that the toner composition be redesigned for each different application.